Human joints are susceptible to degeneration from disease, trauma, and long-term repetitive use that eventually lead to pain. In the spine, degenerative spine disease is a major cause of chronic disability in the adult working population. Spinal degeneration is a normal part of aging, and neck and back pain are one of life's most common infirmities.
There are many potential sources of back pain, and finding the specific cause is often a confounding problem for both patient and doctor. Pain can originate from bone, joints, ligaments, muscles, nerves and intervertebral disks, as well as other paravertebral tissues. For acute pain due to structural damage of the spine, treatments that repair the damaged area, such as by mechanical fixation devices like fixation plates or rods, have proven effective. These treatments generally involve the immobilization of the damaged area through spine restabilization, thus altering the load sharing of each segment. This is commonly performed by in situ, on lay, interbody, and other fusion procedures that improve loading of the diseased subchondral defects (e.g., edema or lesions), and load transfer to other areas and implantable devices. When fusion is not desirable, implantable motion preservation devices may accomplish this load transfer and improve stability while reducing pain.
Unlike acute injuries or trauma of the spine, current treatments for chronic back pain due to degenerative disc disease or osteoarthritis have not proven as reliable or effective. Many medical practitioners focus treatment on the intervertebral disc, because they have attributed disc degeneration, more specifically the initial delamination of the annulus, followed by nucleus dehydration and subchondral bone changes, as a continuum of events as the degenerative disease cascade progresses. Current treatments comprise, for example, partial or complete fusion to immobilize and/or isolate the damaged area, intervertebral disc repair or replacement, nucleus repair or replacement, and corpectomy.
The rationale for treating the disc as a pain source in the spine is similar to the popular theory within the orthopedic community that joint pain, such as that found in the knee or hip, results from bone-on-bone contact or inadequate cartilage cushioning. These conditions are believed to frequently result from the progression of osteoarthritis, which is measured in terms of narrowing of the joint space. Therefore, the severity of osteoarthritis is believed to be an indicator or precursor to joint pain. Most surgeons and medical practitioners thus base their treatments for pain relief on this theory. However, the severity of osteoarthritis, especially in the knee, has been found to correlate poorly with the incidence and magnitude of knee pain. Because of this, surgeons and medical practitioners have struggled to deliver consistent, reliable pain relief to patients, especially if preservation of the joint is desired. Likewise, in the spine, practitioners have not found long-term results from chronic back pain by treating the intervertebral disc as the source and solution of mechanical loading pain of a diseased spinal segment.
Accordingly, it would be desirable to provide a medical procedure that addresses the pain associated with degenerative disc disease or osteoarthritis of the spine, and provides an alternative to a fusion or replacement surgery, which can be highly invasive, risky and irreversible.